1. Field of the Invention
The present invention relates to an aluminum nitride sintered body substrate used in circuit substrates and semiconductor production device parts. More specifically, the present invention relates to an aluminum nitride sintered body suitable for use as a susceptor for heating semiconductor wafers and the like.
2. Description of the Background Art
Conventionally, aluminum nitride sintered bodies have been used for circuit substrates and the like because of their high thermal conductivity and their thermal expansion coefficient that is relatively close to that of silicon. Also, in recent years, the use of aluminum nitride has been proposed for probers for inspecting semiconductor wafers and heaters for heating semiconductor wafers to form conductor films, insulation films, and resist films on semiconductor wafers, for etching semiconductor wafers and the like. In these fields, the temperature distribution of the semiconductor wafer has a significant influence on the characteristics of the product. Since there is a need for a temperature distribution on the surface of the semiconductor wafer to be as uniform as possible, aluminum nitride, which has a relatively high thermal conductivity, is used.
For example, in Japanese Laid-Open Patent Publication No. Hei 11-74064, a metal paste, e.g., tungsten or molybdenum, is screen-printed on ceramic, e.g., aluminum nitride, to serve as a resistance heating body. This is then sintered, resulting in a wafer heating device in which a resistance heating body is embedded.
However, in this type of wafer heating device, the metal paste is applied to the ceramic using screen-printing, but the pattern can be smudged and pinholes can be formed during printing due to pores present on the ceramic surface. Also, when pores are present in the ceramic, transmission of heat generated by the resistance heating body is obstructed on the wafer mounting surface, thus reducing the uniformity of the temperature distribution of the wafer.
The object of the present invention is to overcome the problems described above and to provide a susceptor with superior thermal uniformity by minimizing pores in the aluminum nitride sintered body.